The present invention relates in general to the automobile industry and regards a hybrid supporting structure for a vehicle dashboard and a process for manufacture thereof.
The dashboard of a vehicle is a complex unit, which comprises multiple devices and controls, such as the instrument panel, the assembly for air distribution inside the vehicle passenger compartment, the control panel for the air-distribution assembly, the airbag module, etc. The supporting structure of a dashboard comprises a cross member made of bent sheet metal having an elongated shape along a principal axis and designed to be fixed to the vehicle body. The said cross member constitutes a load-bearing element for supporting the entire dashboard assembly. Hybrid supporting structures are known, in which plastic material is co-moulded on the metal cross member to form an air-distribution assembly and fixing areas on which there are to be installed, for instance, an air-bag module and various electrical or electronic components or devices forming part of the dashboard assembly. In particular, the air-distribution assembly comprises a distribution duct which extends parallel to the cross member and a distribution box defining one or more chambers that communicate with the duct. The air-distribution assembly is obtained by means of injection of plastic material and is anchored on the cross member by co-moulding, i.e., by injection of plastic material on the metal cross member.
One of the problems that are encountered in producing a hybrid supporting structure of this type is represented by the different coefficient of thermal expansion of the cross member and of the plastic material co-moulded thereon. When the dashboard assembly is installed on a vehicle, the heating and cooling cycles produce a differentiated thermal expansion of the part of plastic material and of the metal part of the hybrid supporting structure. Thermal expansion of this sort produces stresses in the plastic material which can bring about its failure.
In order to overcome the aforesaid drawbacks, the subject of the present invention is a hybrid supporting structure for a vehicle dashboard, as well as a process for manufacture thereof, the said structure and process having the characteristics that form the subject matter of the ensuing claims.